Genome-wide identification and expression analysis of the IQD gene family in moso bamboo (Phyllostachys edulis)

Members of the plant-specific IQ67-domain (IQD) protein family are involved in various aspects of normal plant growth and developmental processes as well as basal defence response. Although hundreds of IQD proteins have been identified, only a small number of IQDs have been functionally characterized. Moreover, no systematic study has been performed on moso bamboo. In this study, we performed for the first time a genome-wide identification and expression analysis of the IQD gene family in moso bamboo. We identified 29 non-redundant PeIQD encoding genes. Analysis of the evolutionary patterns and divergence revealed that the IQD genes underwent a large-scale event around 12 million years ago and the division times of IQD family genes between moso bamboo and rice, and, between moso bamboo and Brachypodium, were found to be 20-35 MYA and 25-40 MYA, respectively. We surveyed the putative promoter regions of the PeIQD genes, which showed that largely stress-related cis-elements existed in these genes. The expression profiles of the IQD genes shed light on their functional divergence. Additionally, a yeast two-hybrid assay proved that PeIQD8 can interact with PeCaM2 and that IQ or I in the IQ motif is required for PeIQD8 to combine with CaM2.